Unfledged Wood Pigeon

[Squid]

Hiya, i have just joined this forum in the hope that someone may be able to help me. I have taken a good look around and got some great info, so thank you..
10 days ago I noticed an adult wood pigeon attacking a younger bird out side my garden gate, it was jumping on top of it and plucking its head, the bird couldnt fly and was obviously exhausted....I managed to capture it and i brought it in and put it inside a cat carrier....
I keep birds myself, i have african greys and conures, so I had an idea about feeding it etc...I fed it amall amounts of water via syringe and some food using tweezers, i gave its mashed mixture which i cook for my own birds.
After a few days it started eating by its self, it ate very well and became quite strong and healthly...I transferred it to a budgie cage so it was easier to clean and feed etc plus it had perches and after a while it started perching and seemed quite strong...
After a few days it started flapping frantically and i was very worried that it would injure itself...i couldt let it out in the house because i was so worried about quarantine and spreading any disease to my own flock....
Anyway, last Sunday i decided it was time to release her (i think i did the wrong thing) I released her in the garden and she flew up onto my conservatory and from there into a large fir tree in my garden.....
I am sure i did the wrong thing?, i found this site recently and now I think that she is unfledged and too young...yesterday morning i saw her sitting on my fence by the bird table and today she came up to my bedroom window and just sat there...i got dressed quickly and went outside to catch her but she had gone...ohh i am so angry with myself, i am sure she is too young, or is she ill? I really dont know what to do...she seems to appear early mornings and i know that i will be able to get hold of her if i see her again, should i catch her again and bring her in? and what are the dangers of disease to my captive birds? I do have photos if anyone wants to see?
Please Help
Thank you